The unexpected dewetting during growth of silicene flakes with dendritic pyramids

Silicene growth on graphene has emerged as a novel method for fabricating silicon-based van der Waals heterostructures. However, the silicene flakes produced in this manner are the result of an exotic growth mode characterized by metastable nanostructures with varying degrees of deviation from equilibrium, with large two-dimensional flakes surrounded by a rim that coexist with small 3D islands, and, at large deposits, thick dendritic pyramids separated by a denuded zone. In order to rationalize and control this growth, a model is derived that revisits the dewetting thermodynamics and considers generally ignored adsorption and step-edge energies. The model is investigated using kinetic Monte-Carlo simulations and mean-field rate equations, and implemented by close inspection of microscopy images. This model perfectly reproduces the experimental outcomes, unveiling an anomalous growth mode, and provides guidelines on experimental conditions for high-quality silicene growth. • Production of 100 nm flakes of 2D silicene during the epitaxy of Si on graphene at T=300 K. • Coexistence of metastable 2D flakes surrounded by a rim, and 3D dendritic pyramids. • Quantitative evaluation of atomic energy barriers of diffusion, binding, step-edges stabilization and wetting for Si on Gr, with KMC/microscopy images combination.